The present invention relates to wire cable trays and concerns a coupling for assembling unit sections of such cable tray and ready-to assemble cable tray unit sections so obtained.
As is well known, cable trays in general and wire cable trays in particular are intended to bear and guide all types of high or low tension electrical cables for a wide variety of uses, and in general all resilient conductors or channels which span between different points, such as optical fibres.
Such wire cable trays are formed by a wire structure, generally of metal, formed as a mesh. They are generally but not exclusively in the form of a guttering, normally but not exclusively in a U form, and comprise transverse wires, also known as weft wires, which produce the transverse gutter shape and are regularly disposed along the length of the cable tray, which transverse wires are joined by welds or analogous joints to longitudinal wires also known as warp wires distributed over the whole periphery of the guttering. In this way, a bottom and two lateral sides are present in such cable trays, the upper parts of the sides terminating in a longitudinal edge wire. Other configurations are possible.
Such cable trays can be installed in any possible position, non limiting examples of which are with the bottom horizontal, vertical or inclined to the horizontal.
The present invention relates to assembly of all types of wire cable trays, whatever their shape and the distribution, number, cross section, shape, or nature of the various longitudinal and transverse wires or components which constitute the cable tray, a non limiting example of which is described in European patent EP-A-0 298 825.
Such cable trays are generally formed by unit sections of a predetermined length and must be assembled end to end on site to the desired length and in the desired configuration.
Assembly is achieved using assembly arts which can mechanically join two successive unit sections of cable tray. The assembly parts are generally known as couplings. The term coupling or assembly coupling will be used in the present document.
Numerous couplings for wire cable trays are already known.
Such couplings are available to users as accessories which are sold separately from the cable trays, requiring the user to calculate his coupling requirements. In addition, mounting such couplings normally requires the use of tools or supplementary mounting parts.
Further, such couplings can only be mounted on the cable tray when the unit sections to be assembled have been positioned in the workplace in the precise position for mounting.
Mounting thus takes place under uncomfortable conditions or even where access is difficult as it is generally high up.
French patent FR-A-2 691 590 describes self-fixing cable tray unit sections constituted by asymmetric cable tray modules. In that document, one end of a coupling is permanently welded to one end of the module, the other end of the coupling comprising a coupling pin which links to the end of the next module to be, assembled.
The use of couplings which are permanently and immovably mounted on the cable trays overcomes some of the difficulties mentioned above but creates other problems for the manufacturer and the user of such cable trays, in particular: supplemental welding operations, and a double stock of cable trays with welded couplings and without welded couplings. Further, if a module is cut because of the length of the installation, according to FR-A-2 691 590, separate couplings must be employed in order to be able to use the portion which does not include the welded couplings.
The aim of the present invention is to provide a coupling which is advantageously free of the disadvantages described above.
The present invention seeks to provide a coupling for wire cable trays which is universal in nature, i.e., which can be sold or used separately, or pre-mounted on one end of a cable tray unit section, the cable tray unit section and the coupling being sold in this case as ready-to-assemble with another cable tray unit section, but the coupling can always be dismantled easily.
The invention also seeks to provide a coupling which can be mounted on and can remain in position on a single end of a first cable tray unit section, assembly of a second cable tray unit section using the same coupling not requiring any dismantling of said coupling from the first unit section and being effected very easily.
The invention also seeks to provide a coupling which has the smallest possible play and which produces the most rigid possible bond between cable tray unit sections, which can however be dismantled, and which also ensures good electrical continuity of the cable tray.
We have sought to provide a coupling with which the cable tray unit sections can be mounted and dismantled easily without requiring specific tools or accessory parts.
We have also sought to provide couplings which are positioned in advance on cable tray unit sections to allow the most compact possible stacking thereof for transport.
The invention provides a coupling for assembling two wire cable tray unit sections, which coupling is longitudinally divided into two arms, each arm being provided with mounting means for latching it removably in position on the end zone of a first unit section and on the end zone of a second unit section respectively. The means for mounting the first arm are independent of those of the second arm and can alone render the coupling solid with the first unit section, the means for mounting the second arm on the second unit section comprising at least one resilient catch means which can co-operate with a transverse wire of the second unit section during assembly of the two unit sections.
In general, the wires of the cable trays are metal wires and the coupling is also metal with strength and resilience characteristics which ensure good assembly conditions.
Thus the means for mounting the first arm can autonomously and independently be used to assemble and latch the coupling on the end of a first cable ray unit section, such an assembly being able to be dismantled at any time.
In order to assemble the second unit section on the first unit section provided with the coupling of the invention, the end of the second cable tray unit section is displaced by a relative coupling-cable tray movement and engaged on the second arm of the coupling, the resilient catch means of the second arm alone latching the second unit section in position following the first unit section.
Assembly is achieved by leaving the first arm of the coupling completely latched and mounted on the first unit section, the coupling being in a kind of block with the first unit section.
Advantageously, the coupling is constituted by a part which is generally in the form of a strip, which may or may not be longitudinally or transversely profiled, the dimensions of which are advantageously such that it can be housed between two longitudinal, preferably successive, wires of the cable tray unit sections to be assembled.
The coupling is advantageously but not exclusively positioned in the mesh constituted at the end of each unit section by two successive longitudinal wires and two successive transverse wires, one of these wires being the transverse wire positioned at the end of the unit section to be assembled.
When the cable tray is provided with lateral sides, the mesh comprising the longitudinal edge wire is advantageously selected.
In a preferred embodiment, the strip constituting the coupling has, except for clearances, a width which equals the distance separating two successive longitudinal wires and between which it is to be mounted.
The strip constituting the coupling can be profiled towards the inside or outside of the cable tray by lapping the edges of the strip to produce a coupling which is more rigid where desired.
In a first embodiment, the mounting means for the first arm, which means are used to position, fix and latch the coupling on the first unit section, are constituted by a longitudinal surface which bears on at least one longitudinal wire of the unit section and to each side of this longitudinal bearing surface is a transverse surface which bears on a transverse wire of the unit section, the two transverse bearing surfaces being adapted to bear on two different successive transverse wires of the unit section. The longitudinal bearing surface and the transverse bearing surfaces are such that they exert bearing forces on their respective wires, the forces exerted by the longitudinal bearing surface being in the opposite sense to the forces exerted by the transverse bearing surfaces and these forces, by dint of friction and a slight elastic deformation, locking the coupling on the cable tray unit section.
In this way the longitudinal bearing surface bears on the inside of a longitudinal wire while the transverse bearing surfaces bear on the outside of the transverse wires, or vice-versa.
The longitudinal bearing surface advantageously bears on the two longitudinal wires located either side of the first arm during mounting.
A guide mark allows precise positioning of the first arm on the corresponding unit section.
The means for mounting the first arm also advantageously comprise a stop means such as a housing or recess which can optionally, by elastic deformation, at least partially house a transverse wire.
The stop means latches the coupling on its unit section, the latching means also serving as a positioning means.
In order to ensure precise positioning on the unit section, the first arm can comprise an abutment in the form, for example, of a tab which will house one of the transverse wires. The stop means can be disposed towards this abutment or on the opposite side.
The transverse bearing surfaces can be constituted by the strip itself or by its edges.
The longitudinal bearing surface can be constituted by a transverse elongation of the strip forming the coupling, the elongation having a shape which can marry with the shape of the longitudinal wire or wires on which this surface will bear. The longitudinal bearing surface can be constituted by several part surfaces all having the same function.
In another embodiment, the means for mounting and positioning the first arm are constituted by at least one tab which can receive a first transverse wire and by a loop which can receive a second transverse wire, the tab/loop assembly latching it on the first cable tray unit section.
The first arm of the coupling, its tab and its loop are advantageously dimensioned so that the tab and the loop bear on their respective wire, engagement of the transverse wire in the loop housing advantageously being made by elastic deformation of the loop.
In this other embodiment and when the loop is located close to the free end of the first arm advantageously a second loop constituting a hinge can be located close to said loop so that the coupling can be turned back along the cable tray in an opposed position to its latched position, a ratchet or equivalent means maintaining the coupling in the turned back position.
The second arm of the coupling comprises at least one resilient catch means which can co-operate with a transverse wire of the second unit section of the cable tray.
This resilient catch means can be located so as to co-operate either with the transverse wire located at the end of the second unit section or with the next transverse wire.
The term xe2x80x9cresilient catch meansxe2x80x9d means any means located on the second arm of the coupling which requires an elastic deformation either of the coupling or of the cable tray or of both at the same time to mount the second cable tray unit section, the coupling and the cable tray regaining their initial shape after latching.
The resilient means can be disposed close to the centre of the coupling or close to the free end of the second arm, depending on which it co-operates with the transverse wire of the end of the second unit section or with the next transverse wire respectively.
Non limiting examples of this resilient means are a resilient guide tongue inclined with respect to the general orientation of the coupling, located close to end of the arm and provided with a housing formed by a crook, for example. As another example, it may consist of a pin constituting a ramp requiring elastic deformation, after which pin there may or may not be a specific housing for the transverse wire.
This pin can be obtained and produced by any means, such as forming to size, stamping, cutting, or attaching parts.
The dimensions of the second arm are advantageously such that it can be housed between two successive longitudinal wires, as with the first arm, the second and the first arm being formed in one and the same strip.
The mounting means for the second arm can comprise a plurality of resilient catch means, each means co-operating with a different transverse wire.
The mounting means for the second arm can also comprise a guide means such as at least one tongue located close to the free end of the arm. The resilient catch means may or may not be located close to the guide means.
Close to its centre, the coupling can comprise a pin forming an abutment on which the transverse wires of the end of the two assembled unit sections will bear when mounted. This pin can be constituted by a tab of the first arm of the coupling, in the case where this first arm comprises a tab located close to the transverse bearing surface near the centre of the coupling.
The means for mounting the second arm and the means for mounting the first arm are preferably located so as to reduce play to a minimum, the second arm and the first arm in the assembled position on their respective unit section being under slight tensile stress.
The invention also concerns the use of the couplings described to produce a wire cable tray unit section in which one end comprises two couplings as described above, mounted and latched onto said unit section by their first arms, the other end of the unit section being free to accept the second arms of two other couplings mounted and latched onto a further unit section to assemble the unit sections together.
Such a wire cable tray unit section comprising couplings of the invention already mounted by their first arms will be termed a pre-mounted unit section.
The invention is thus also relative to a pre-mounted unit section.
Such a pre-mounted unit section is very easy to assemble on the free end of a further pre-mounted, or a non pre-mounted, unit section.
The two unit sections are simply aligned slightly on a slant and the second arms of the two couplings are engaged in the housings of the second unit section which receives them, the housing advantageously being located between two successive longitudinal wires.
After bringing the two unit sections close together, the two unit sections are pushed together axially to engage the resilient catch means provided on each second arm on the transverse wire with which they co-operate.
When the unit section has a U cross section, the two couplings of the pre-mounted unit section are symmetrically located on the lateral sides of the unit section. These couplings can advantageously be housed between the longitudinal edge wire and the next longitudinal wire.
This produces the considerable advantages of the invention, the cable tray unit section being capable of being supplied either pre-mounted or not pre-mounted.
The range of cable tray production does not need to be changed at all. It is sufficient to mount the couplings of the invention onto unit sections to obtain pre-mounted unit sections, depending on demand, for example just before transporting the unit sections. This avoids any heavy welding type operation and has the advantage that bare unit sections without couplings can always be recovered when required.
The design of the couplings of the invention also means that the pre-mounted unit sections can be transported very easily stacked one top of the other.
Dismantling the couplings of the invention, the same as for mounting, does not require any special tools or accessories. However, if necessary a tool such as a screwdriver can be used to lever and facilitate mounting and dismantling the couplings.
The coupling may be constituted by a single one-piece strip which has a shape which can carry out all of the desired functions at the desired positions. It is also possible to produce it in composite form by combining the different components carrying out the different functions, for example by welding or other means on a common support, for example in the form of a strip.